There is a Rygel instance on my Ubuntu ran using Settings → Sharing.
It is discovered in VLC on a Windows machine but not discovered in VLC on Android and on the Smart TV (IFFALCON). All on the same local WiFi.
What could be the reason and how can I diagnose?
VLC on Android is weird, that should just work. (Though I recommend BubbleUPnP on Android and have it use VLC for playing stuff)
Most likely the TV does not like the version of UPnP Rygel implements.
Please stop sharing from the settings and run Rygel from the console:
G_MESSAGES_DEBUG=all rygel -g 5 | tee rygel.log
Once the initial storm of messages is over, try start your Smart TV and see if you get any log messages. What to do next depends on what you see 
Thanks for your help.
I’ve run Rygel from the console as you suggested. First, it appeared in the Android’s VLC. Maybe a coincidence, though.
Second, it didn’t appear on the TV, and no new messages when I turned the TV on and entered into the media player (where all DNLA servers would appear). However, also there were no new messages when I discovered the Rygel instance in VLC, only when I open the instance.
As an important note: MiniDLNA that runs on the same machine is seen on the same TV. Does this give any clue?
In the screenshot below it’s seen that both appear in the mobile VLC.
That points to version mismatch. Unfortunately the fact that it does not try to connect to rygel points to SSDP already. Are you comfortable with tcpdump or wireshark?
